Filter cups and filter cages are well-known devices often used in vacuums to support and/or protect a filter. Selected prior art filter cups and filter cages are described below.
U.S. Pat. No. 4,185,974 teaches a filter assembly 80 having a collar 82. The collar is designed to be secured to the lid 22. A filter cage 84 extends downwardly from the collar. The cage is comprised of a plurality of ribs 86. The ribs are constructed of plastic. The ribs are oriented so that the filter cage tapers from the portion secured to the collar to a bottom wall 94 of the cage. The ribs permit fluid, such as air, to flow between them into the filter element 150. An annular sleeve 106 extends upwardly from the bottom wall 94. A plurality of fluid slots are located in the annular sleeve.
U.S. Pat. No. 4,906,265 teaches a similar structure to that described in U.S. Pat. No. 4,185,974. More particularly, U.S. Pat. No. 4,906,265 teaches a filter assembly having a filter cage 20 having an open end and a closed end 24. The cage 20 is comprised of a plurality of vertical struts 26 which are circumferentially spaced apart. A plurality of open spaces 27 are defined by and between the vertical struts 26. The struts 26 are taught to taper slightly inwardly toward the closed end 24. A filter is located outside of the filter cage.
U.S. Pat. No. 5,344,559 depicts and describes a filter cartridge having two cylindrical filter cages 2, 3. Each filter cage has a plurality of openings 10 to permit fluid through the cages. A filter element 1 is disposed between the cages. Both ends of both filter cages are open.
U.S. Design Pat. No. D186,583 teaches a dust bag holder for a vacuum cleaner. The dust bag holder has an upper, circumferential lip connected to an upper portion of the holder. The holder has a plurality of slots located over the entire body portion. A plurality of holes is also located in the base of the holder.
U.S. Design Pat. Nos. D495,105 and D495,458 depict a filter cup assembly for a vacuum cleaner having an upper, circumferential lip and a mesh-like body downwardly depending from the lip. The mesh-like material appears to encircle the body except where four ribs extend between the lip and a bottom of the cup. A filter element is shown as being located within the filter cup in FIG. 2. The bottom of the filter cup, as shown in FIG. 6, is substantially solid.
U.S. Patent Application Publication No. US 2002/0011050 teaches a cylindrical separator 40, best seen in FIG. 11. Air passes through a preliminary filter element 44 of the separator. The air is drawn downwardly through a filter cup 120. A raised portion 70 of a motor cover 66 closes the base of the separator, except a plurality of apertures 72 in the cover 66 allow air to flow from the separator through the cover and escape into the atmosphere.
The prior art filter cups and filter cages described above suffer from several disadvantages. Specifically, the prior art cups and cages fail to protect the filter from directly impinging dirt and debris thus causing the filter to become clogged. Additionally, the prior art cups and cages fail to protect the filter from dirt and debris and also permit a sufficient quantity of air to flow through them and into the filter. In light of at least these disadvantages of the prior art devices, it would be advantageous to have a filter cup that protected the filter from dirt and debris from becoming lodged therein yet which freely permits air to pass through to the filter.